Energy absorbing tube support for furnace

ABSTRACT

A deformable and replaceable energy absorbing structure mounted between the furnace floor tubes and floor tube support truss to absorb impact from falling slag and prevent tube damage. A beam, such as an I-beam extends from the supporting structure and is adapted to hold a deformable structure. A tie bar attached to the floor tube panel extends across the panel and rests upon the deformable structure. This arrangement is provided at as many contact points between the floor tube panel and support structure as necessary to support the dead weight of the tubes while still providing suitable energy absorption characteristics.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is generally related to industrial furnaces andparticularly to the floor tube supports in such furnaces.

2. General Background

In industrial furnaces such as those used by utilities, heat exchangetubes which form the walls and floor carry a liquid that serves as aheat exchange medium. The tubes must be protected from cracking orcrushing in order to operate efficiently. Slag particles carried in thehot furnace gases collect on the exposed surfaces in the upper furnaceand, eventually, fall onto the floor tubes of the furnace. Even thoughfurnace floors generally are sloped to shed slag and other deposits, theimpact and weight of the slag has damaged or crushed the floor tubes incertain furnaces. Such furnaces have the problem of having rigidmountings for the floor tubes that force the tubes to absorb the impactand weight of the slag. This leads to support truss and tube damage,reduced operating efficiency, and the need for outages to make repairsand install new materials which also will be subject to damage. Thisresults in a need in such furnaces for floor tube mountings that willprevent damage to the floor tubes and support trusses by absorbing theimpact and weight of falling slag and that are replaceable at less costthan that of the heat exchange tubes.

SUMMARY OF THE INVENTION

The invention addresses the above need. What is provided is a deformableand replaceable energy absorbing structure between the furnace floortubes and the floor tube supporting truss. When necessary to provide forgreater distribution of the load over the supporting structure,additional vertical trusses may be added and the number of contactpoints between the vertical trusses and tube panels may be increased. Abeam, such as an I-beam, extends from the supporting structure and isadapted to hold a deformable structure. A tie bar attached to the floortube panel extends across the panel and rests upon the deformablestructure. This arrangement is provided at as many contact pointsbetween the floor tube panel and support structure as necessary tosupport the dead weight of the tubes while still providing suitableenergy absorption characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature and objects of the presentinvention reference should be made to the following description, takenin conjunction with the accompanying drawings in which like parts aregiven like reference numerals, and wherein:

FIG. 1 is a sectional view of one side of the interior of a furnace.

FIG. 2 is an enlarged view of the area indicated in FIG. 1 by thenumeral 10.

FIG. 3 is a view taken along lines 3—3 in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, FIG. 1 is a sectional side view illustratingthe interior of one side of a furnace. Heat exchange tubes 2 aresupported at an angle by floor support truss 4 such that heat exchangetubes 2 extend downward generally toward the center of the furnace. Onlyone side of the furnace and heat exchange tubes contained therein areshown for ease of illustration. The invention is generally indicated bythe numeral 10 in FIG. 1 and is illustrated in an enlarged view in FIG.2.

Deformable energy absorbing structure 10 has an I-beam 12 attached atvarious points to floor support truss 4 to distribute the load over thetruss structure. I-beam 12 has support lugs 14 attached across its widthand extending upward to define a channel sized to receive stand-off 16best seen in FIG. 3. Stand-off 16 absorbs the impact and weight offalling slag by deforming or crushing at an energy level less than thatrequired to damage heat exchange tubes 2. Stand-off 16 is formed in thepreferred embodiment from three and one-half inch schedule forty pipe.

As best seen in FIG. 2 and 3, a tie bar support lug 18 is attached totwo adjacent heat exchange tubes 2 and a second tie bar support lug 18is spaced along the length of tubes 2 such that tie bar 20 may be fitbetween the support lugs 14. A pin 22 placed through tie bar supportlugs 18 and under tie bar 20 serves to hold tie bar 20 in positionagainst tubes 2 such that tie bar 20 rests upon stand-off 16. Tie barsupport lugs 18 and pins 22 are spaced apart at suitable intervalsacross tubes 2 to provide the necessary supporting contact to tubes 2.In this manner, several tie bars spaced apart under tubes 2 contact anumber of stand-offs 16 and distribute the weight of tubes 2 across thetie bars. This prevents small contact points on one or two tubes whichwould damage the tubes. The number of contact points and trussesrequired will depend on the size of the furnace and the number of floortubes involved.

Because many varying and differing embodiments may be made within thescope of the inventive concept herein taught and because manymodifications may be made in the embodiment herein detailed inaccordance with the descriptive requirement of the law, it is to beunderstood that the details herein are to be interpreted as illustrativeand not in a limiting sense.

What is claimed as invention is:
 1. In a furnace for boilers having arow of heat exchange tubes forming the floor of the furnace, adeformable and replaceable energy absorbing structure mounted betweenthe furnace floor tubes and floor tube support truss, comprising: a. anI-beam mounted on the floor tube support truss, said I-beam havingsupport lugs attached thereto across the I-beam width so as to define achannel between the support lugs; b. a deformable stand-off placed inthe channel defined by the support lugs; c. a tie bar positioned betweensaid stand-off and the heat exchange tubes; d. tie bar support lugsattached to two adjacent heat exchange tubes and spaced apart along thelength of the heat exchange tubes such that the tie bar will fit betweensaid tie bar support lugs; and e. a pin placed through said tie barsupport lugs under said tie bar.
 2. In a furnace for boilers having arow of heat exchange tubes forming the floor of the furnace, adeformable and replaceable energy absorbing structure mounted betweenthe furnace floor tubes and floor tube support truss, comprising: a. asupport member mounted on the floor tube support truss; b. a deformablestand-off positioned between said furnace floor tubes and said supportmember; c. a tie bar positioned between said stand-off and the heatexchange tubes; d. tie bar support lugs attached to two adjacent heatexchange tubes and spaced apart along the length of the heat exchangetubes such that the tie bar will fit between said tie bar support lugs;and e. a pin placed through said tie bar support lugs under said tiebar.
 3. The deformable and replaceable energy absorbing structure inclaim 2, wherein said support member comprises an I-beam.
 4. Thedeformable and replaceable energy absorbing structure in claim 2,wherein said deformable stand-off is tubular.